Process, apparatus and system for creating extrudable material having color effects and products made with extrudable material created with same

ABSTRACT

A process and associated system for creating color effects in extrudable material, such as plastic and metal for example, are presented. Flows of first and second viscous materials of respective colors are provided and then combined in a predetermined pattern to form a stream of combined viscous material. In a first aspect, the flow rate of the first viscous material is caused to vary over time in order to vary an amount of the first viscous material in the stream. In a second aspect, which may be used alone or in combination with the first aspect, the first and second viscous materials have distinct viscosities to reduce an amount of color blending between the first color and the second color in the stream of combined viscous material. A static mixer may then be used to apply a predetermined dividing, overturning and combining motion to the stream of combined viscous material to partially mix the first viscous material and the second viscous material, such that upon exiting the static mixer, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material. Sheets of extrudable material may be created using such process and used in the manufacturing of many different products including for example kayaks and stand-up paddle boards.

FIELD OF THE INVENTION

The present invention relates generally to the field of extrusion processes and extrudable materials created using such processes, including for example plastic or metal materials. More specifically, the present invention relates to processes and associated apparatuses and systems for creating extrudable materials having color effects as well as to products made with extrudable materials having color effects created using such processes.

BACKGROUND

Extrusion processes are commonly used in a variety of different industries, and with a multitude of different types and grades of material, for forming and shaping these materials into articles.

Extruded products, whether plastic, metal or some other material, are often uniform in color. In some cases, the extruded products are formed of several layers of material, including one or more visible, outer layers and one or more hidden, inner layers, where these layers may differ in color.

In today's competitive market place, it is important for companies to have an edge that distinguishes their product from a competitor's product. One way to create a product that distinguishes itself from a competitor's product is to provide the product with an aesthetically pleasing and/or original appearance. Consumers are typically attracted to products having a visually appealing look.

In the field of extruded products, one method for giving the end products a visually appealing look is to create special color effects in the material of the product. Existing methods for producing color effects in extruded material, such as plastic for example, include lamination techniques, wherein multiple different layers of colored material are joined together to form a multi-colored sheet, and imprinting techniques wherein an imprinted film is adhered to the material. Unfortunately, these processes require treating the material after it has been extruded and formed. This can be both costly and time consuming.

Other methods, such as the one described for example in U.S. Pat. No. 7,204,944, allow producing color effects in the form of color bands in the extruded material by combining flows of viscous material of multiple colors during the extrusion process to form a stream of viscous material characterized by bands of different colors. The contents of the aforementioned document are incorporated herein by reference. While approaches of the type described above may allow creating extruded material having a pleasing and original visual appearance, the visual effects that may be produced tend to be limited. In order to attract the attention of consumers, it is desirable to create a variety of original color effects in extruded materials include some that may differ from those that may be created by methods of the type proposed in U.S. Pat. No. 7,204,944.

As such, a need exists in the industry to provide methods for producing visually appealing color effects in extrudable material, such as plastic and metal.

SUMMARY

In accordance with a first aspect, a process for creating color effects in extrudable material is described. The process comprises providing a flow of a first viscous material of a first color, wherein the flow of the first viscous material is associated with a first rate of flow and wherein providing the flow of the first viscous material of the first color includes varying the first rate of flow over time. The process also comprises providing a flow of a second viscous material of a second color different from the first color, wherein the flow of the second viscous material is associated with a second rate of flow. The process also comprises combining in a predetermined pattern the flow of the first viscous material and the flow of the second viscous material to form a stream of combined viscous material.

Varying the rate of flow of the first viscous material over time may allow modulating over time an amount of the first viscous material, relative to an amount of the second viscous material, that finds itself in the stream of combined viscous material at different moments in time, which may allow the color effects created to vary over time and may allow creating wave-like color gradation effects.

In some specific practical implementations, varying the first rate of flow over time may include causing the first rate of flow to oscillate between a lower flow rate threshold and an upper flow rate threshold over a time interval. The time interval may have any suitable duration. In specific non-limiting implementations, the duration has ranged between at least about 20 seconds and about 1 minute however any suitable duration for the time interval may be contemplated including shorter and intervals or more lengthy intervals. Optionally, in some embodiments, the process may include setting the lower flow rate threshold and/or the upper flow rate threshold and/or the time interval in order to control at least in part visual characteristics of the color pattern in the stream of combined viscous material. In specific practical implementations, any suitable mechanism may be provided to enable a user to provide control command for setting or modifying the lower flow rate threshold and/or the upper flow rate threshold and/or the time interval. Such suitable mechanism may include, without being limited to, providing user operable controls in communication with an electronic control element.

In some specific practical implementations, the second rate of flow associated with the flow of the second viscous material may be kept substantially constant over time. Alternatively, the second rate of flow may also be caused to vary over a time period so that the flows of both the first viscous material and the second viscous material are caused to vary over time. In such alternative implementations, the time intervals over which the first viscous material and the second viscous material vary need not be the same.

In some specific practical implementations, the second rate of flow associated with the second viscous material of the second color may be lower than the first rate of flow. In such implementations, the first viscous material constitutes a larger portion of the resulting stream of combined viscous material than the second viscous material. In specific practical implementations, the second rate of flow may be no more than 50% of the first rate of flow, preferably no more than 30% of the first rate of flow and more preferably no more than 20% of the first rate of flow.

In some specific practical implementations, the first viscous material has a first viscosity and the second viscous material has a second viscosity, wherein first viscosity may be distinct from the second viscosity to reduce an amount of color blending between the first color and the second color in the stream of combined viscous material.

In some specific practical implementations, the first viscous material is associated with a first high load melt index (first HLMI) and the second viscous material is associated with a second high load melt index (second HLMI), where the first HLMI may be greater than the second HLMI. The difference between the high load melt indices of the first and second viscous mates may be selected in such a way as to control the amount of blending that may occur between the different colors of the first and second viscous materials. In specific practical implementations, the first HLMI may be at least about ten times (10×) the second HLMI; the first HLMI may also be at least about twenty times (20×) the second HLMI; the first HLMI may also be at least about one hundred times (100×) the second HLMI. Typically, the greater the difference between the HLMIs the lesser the extent of the color blending in the stream of combined viscous material.

In some specific practical implementations, the first viscous material and the second viscous material may be viscous plastic materials, metal materials or some other viscous materials.

In some specific practical implementation, the first color of the first viscous material may be a translucent color.

In some specific implementations, the process may also comprises using a static mixer to apply a predetermined dividing, overturning and combining motion to the stream of combined viscous material to partially mix the first viscous material and the second viscous material, such that upon exiting the static mixer, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material. In a specific practical implementation, the static mixer may include a helical mixer.

In some specific implementations, after applying the dividing, overturning and combining motion, the process may include the step of forming the stream of combined viscous material into a sheet or, alternatively, forming the stream of combined viscous material into a tube.

In some specific implementations, after applying the dividing, overturning and combining motion, the process may include feeding the stream of combined viscous material through a die for forming a sheet of material comprising a wave-like color gradation effect.

In accordance with a second aspect, a process for creating color effects in extrudable material is described comprising providing a flow of a first viscous material of a first color and providing a flow of a second viscous material of a second color different from the first color. The process also comprises combining in a predetermined pattern the flow of the first viscous material and the flow of the second viscous material to form a stream of combined viscous material. The process also comprises using a static mixer to apply a predetermined dividing, overturning and combining motion to the stream of combined viscous material to partially mix the first viscous material and the second viscous material, such that the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material, wherein:

-   -   i) the flow of the first viscous material is associated with a         first viscosity; and     -   ii) the flow of the second viscous material is associated with a         second viscosity, the first viscosity being distinct from the         second viscosity to reduce an amount of color blending between         the first color and the second color in the stream of combined         viscous material when the static mixer applies the predetermined         dividing, overturning and combining motion to the stream of         combined viscous material.

In some specific practical implementations, the first viscous material is associated with a first high load melt index (first HLMI) and the second viscous material is associated with a second high load melt index (second HLMI), where the first HLMI may be greater than the second HLMI. The difference between the high load melt indices of the first and second viscous mates may be selected in such a way as to control the amount of blending that may occur between the different colors of the first and second viscous materials. In specific practical implementations, the first HLMI may be at least about ten times (10×) the second HLMI; the first HLMI may also be at least about twenty times (20×) the second HLMI; the first HLMI may also be at least about one hundred times (100×) the second HLMI. Typically, the greater the difference between the HLMIs the lesser the extent of the color blending in the stream of combined viscous material.

In a specific, non-limiting example of implementation, processes of the type described above may be implemented in a system for manufacturing plastic sheets. The system may include a die, a feed block and at least two extruders. The extruders may each be configured to mix and heat plastic granules, for producing a generally homogeneous, viscous plastic mixture. In the context of the present invention, at least two of the extruders produce plastic mixtures of different colors and of different viscosities. The feed block is configured to combine the flows of viscous plastic released by the different extruders into a single stream of combined viscous material. The single stream of viscous plastic generated by the feed block may be fed through a static mixer pipe. The static mixer pipe is configured to act on the single stream of combined viscous material to partially mix the stream and create a color pattern in the stream of combined viscous material. The die receives the partially mixed stream of combined viscous material from the static mixer pipe, and may be configured to shape the stream into its final product form, such as a sheet or a tube, among many other possibilities.

In accordance with a third aspect, a system for creating color effects in extrudable material is provided, the system comprising a first extruder for providing a flow of a first viscous material of a first color, the first extruder providing the flow of the first viscous material at a first rate of flow, the first extruder being in communication with a flow rate controller configured for varying the first rate of flow over time. The system further comprises a second extruder for providing a flow of a second viscous material of a second color different from the first color, the second extruder providing the flow of the second viscous material at a second rate of flow. The system further comprises a feed block for combining the flow of the first viscous material and the flow of the second viscous material to form a stream of combined viscous material.

In some specific practical implementations, the flow rate controller associated with the first extruder may include an electronic control element configured for causing the first rate of flow to vary over time at least in part by causing a variation in a speed of operation of an extruder screw in the first extruder. More specifically, the flow rate controller may include a variable speed motor configured for operating the extruder screw of the first extruder and an electronic control element programmed for controlling the variable speed motor. The electronic control element may be programmed to cause the first rate of flow to vary over time at least in part by causing the variable speed motor to vary the speed of operation of the extruder screw.

In a specific practical implementation, the flow rate controller may be configured for varying the first rate of flow over time at least in part by causing the first rate of flow to oscillate between a lower flow rate threshold and an upper flow rate threshold over a time interval. Optionally, in some embodiments, the flow rate controller may provide one or more user operable controls for allowing a user to set the lower flow rate threshold and/or the upper flow rate threshold and/or the time interval in order to control at least in part visual characteristics of the color pattern in the stream of combined viscous material exiting the system.

In some specific practical implementations, the second rate of flow associated with the flow of the second viscous material may be kept substantially constant over time. Alternatively, the second rate of flow may also be caused to vary over a time period so that the flows of both the first viscous material and the second viscous material are caused to vary over time. In such alternative implementations, the time intervals over which the first viscous material and the second viscous material vary need not be the same.

In some specific practical implementations, the second rate of flow associated with the second viscous material of the second color may be lower than the first rate of flow. In such implementations, the first viscous material constitutes a larger portion of the resulting stream of combined viscous material than the second viscous material. In specific practical implementations, the second rate of flow may be no more than 50% of the first rate of flow, preferably no more than 30% of the first rate of flow and more preferably no more than 20% of the first rate of flow.

In some specific practical implementations, the system may further comprise a static mixer for receiving the stream of combined viscous material from the feed block. The static mixer is configured to apply a predetermined dividing, overturning and combining motion to the stream of combined viscous material to partially mix the first viscous material and the second viscous material such that, upon exiting the static mixer, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material.

In some specific practical implementations, the system may further comprise a die for receiving the stream of combined viscous material from the static mixer, the die being configured for forming the stream of combined viscous material into a sheet or into a tube.

In some specific practical implementations, the system may further comprise at least one additional extruder for providing at least one additional flow of a third viscous material and a combining device for combining the stream of combined viscous material released by the static mixer with the at least one additional stream of the third viscous material provided by the at least one additional extruder. The combining device may be configured for forming a co-extruded stream having at least two layers using the stream of the third viscous material and the stream of combined viscous material.

In accordance with a fourth aspect, a system for creating color effects in extrudable material is provided. The system comprises a first extruder for providing a flow of a first viscous material of a first color and a second extruder for providing a second viscous material of a second color different from the first color. The system further comprises a feed block for combining the flow of the first viscous material and the flow of the second viscous material to form a stream of combined viscous material. The system further comprises a static mixer for receiving the stream of combined viscous material from the feed block, wherein the static mixer is configured to apply a predetermined dividing, overturning and combining motion to said stream of combined viscous material to partially mix the first viscous material and the second viscous material such that, upon exiting the static mixer, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material. The flow of the first viscous material is associated with a first viscosity and the flow of the second viscous material is associated with a second viscosity, the first viscosity being distinct from the second viscosity to reduce an amount of color blending between the first color and the second color in the stream of combined viscous material when the static mixer applies the predetermined dividing, overturning and combining motion to the stream of combined viscous material.

In accordance with another aspect, a process for manufacturing a plastic article comprising color effects is presented. The process comprises molding two or more of the manufactured sheets of extrudable material using thermoforming to shape the two of more manufactured sheets into a kayak shape, at least one of the two or more of the manufactured sheets having color effects created using a process of the type described above.

In specific practical implementations, an other one of the two or more of the manufactured sheets may have a uniform color or, alternatively, may also have color effects created using a process of the type described above.

In specific practical implementations, the process may be suitable for use during manufacturing of many different types of products including, but without being limited to, kayaks, sleds and stand-up paddle boards amongst many others.

In accordance with another aspect, a sheet of extrudable material having color effects is presented, the sheet of extrudable material being comprised of a first viscous material of a first color and a second viscous material of a second color different from the first color, wherein the first viscous material has a first viscosity and the second viscous material has a second viscosity, the first viscosity being distinct from the second viscosity to reduce an amount of color blending between the first color and the second color in the sheet.

In some specific practical implementations, the first viscous material of the sheet is associated with a first high load melt index (first HLMI) and the second viscous material is associated with a second high load melt index (second HLMI), where the first HLMI may be greater than the second HLMI. The difference between the high load melt indices of the first and second viscous mates may be selected in such a way as to control the amount of blending that may occur between the different colors of the first and second viscous materials. In specific practical implementations, the first HLMI may be at least about ten times (10×) the second HLMI; the first HLMI may also be at least about twenty times (20×) the second HLMI; the first HLMI may also be at least about one hundred times (100×) the second HLMI.

In accordance with another aspect, a process for creating color effects in extrudable material is described in which the process comprises:

-   -   a) providing a flow of a first viscous material of a first         color;     -   b) providing a flow of a second viscous material of a second         color different from the first color;     -   c) combining in a predetermined pattern the flow of the first         viscous material and the flow of the second viscous material to         form a stream of combined viscous material;     -   d) using a static mixer applying a predetermined dividing,         overturning and combining motion to said stream of combined         viscous material to partially mix the first viscous material and         the second viscous material, such that such that upon exiting         the static mixer, the first material of the first color and the         second material of the second color form a color pattern in the         stream of combined viscous material, wherein the color pattern         in the stream is configured at least in part based on a radial         orientation of the static mixer.

In some specific practical implementations, the process may comprise altering the color pattern in the stream by performing a rotation of the static mixer by a pre-determined rotation amount to change the radial orientation of the static mixer. In specific practical implementation, the pre-determined rotation amount may be established based on an internal structure of the static mixer such that upon exiting the static mixer a desired effect may be achieved in the stream of viscous material. In specific practical implementations, the pre-determined rotation amount may be a rotation of about 45°, 90°, 135° or 180°.

All features of embodiments which are described in this disclosure and are not mutually exclusive can be combined with one another. Elements of one embodiment can be utilized in the other embodiments without further mention.

Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of specific embodiments of the present invention is provided herein below with reference to the accompanying drawings in which:

FIG. 1 illustrates a system for manufacturing plastic sheets, according to a non-limiting example of implementation of the present invention;

FIG. 2 depicts components of a flow rate controller that may be used in connection with an extruder of the system of FIG. 1;

FIG. 3 depicts an electronic control element of the flow rate controller of FIG. 2 in accordance with a non-limiting embodiment of the present invention;

FIGS. 4A and 4B are charts illustrating variations in a speed of operation of an extruder screw in order to cause variation in a flow rate in connection with an extruder of the system of FIG. 1;

FIG. 5A shows color effects that may be produced in extrudable plastic material using a system of the type shown in FIG. 1 in which the flow rate controller maintains a constant flow rate;

FIG. 5B shows color effects that may be produced in extrudable plastic material using a system of the type shown in FIG. 1 in which the flow rate controller varies the flow rate over time of the material released by an extruder;

FIG. 6 depicts an example of a possible structural configuration for a feed block shown in FIG. 1;

FIG. 7 is a perspective view of a helical static mixer;

FIG. 8 is a perspective view of a different type of static mixer;

FIG. 9A shows examples cross-sectional views of combined streams of viscous material entering the static mixer 108 of the system 100 shown in FIG. 1 in accordance with non-limiting examples of implementation, the examples including (a) a first viscous material (“A”) only; (b) first viscous material (“A”) and second viscous material (“D”); and (c) first viscous material (“A”), second viscous material (“D”) and third viscous material (“E”);

FIGS. 9B, 9C and 9D shows other examples of cross-sectional views of combined streams of viscous material entering the static mixer 108 of the system 100 shown in FIG. 1 in accordance with non-limiting examples of implementation;

FIG. 10 illustrates a combined stream of viscous material as it exits the static mixer in accordance with a non-limiting implementation;

FIG. 11A depicts a sheet of plastic with wave-like color gradation effects created in accordance with a non-liming example of implementation of the invention;

FIG. 11B depicts a tube of plastic with wave-like color gradation effects in accordance with another non-liming example of implementation of the invention;

FIG. 12 is a flowchart illustrating a process for creating color effects in extruded material according to an example of implementation of the present invention; and

FIG. 13 depicts a system for manufacturing plastic sheets according to a variant of implementation of the present invention;

FIG. 14A shows kayaks manufactured using plastic sheets of extrudable material created using a process embodying aspects of the invention;

FIGS. 14B and 14C show top plan and side views respectively of a stand-up paddle board (SUP) manufactured using plastic sheets of extrudable material created using a process embodying aspects of the invention.

In the drawings, embodiments of the invention are illustrated by way of examples. It is to be expressly understood that the description and drawings are only for the purpose of illustration and are an aid for understanding. They are not intended to be a definition of the limits of the invention.

DETAILED DESCRIPTION

The present invention is directed to a process and apparatus for creating color effects in extruded material, such as plastic or metal.

In the following examples of implementation, the present invention will be described for use in creating color effects in extruded plastic material. However, it is to be appreciated that the invention is not limited to any particular type of material. Rather, the concepts described in the present document may be applied to different types and grades of extrudable material.

FIG. 1 depicts a system 100 for manufacturing plastic sheets, according to a non-limiting example of implementation of the present invention. The system 100 shown is formed of several components, including a die 102, a feed block 104, a first (primary) extruder 106 for providing a first material (“A”) and one or more secondary extruders 120 ₁, . . . , 120 _(N), where the number N of secondary extruders 120 ₁, . . . , 120 _(N) in the system 100 is at least one.

Note that, in alternative embodiments, the system 100 may include two or more secondary extruders 120 ₁, . . . , 120 _(N).

Extruder 106 and each extruder 120 ₁, . . . 120 _(N) is operative to mix and heat plastic granules. The granules are heated to a predetermined temperature, sufficient to cause melting of the granules for producing a homogeneous, viscous plastic mixture.

Examples of the different types of thermoplastics that can be extruded include: LDPE, HDPE, ABS, polystyrene, polypropylene, acetates, butyrates, nylons, polyphenylene sulfides, acetals, polycarbonates and thermoplastic rubbers and polyesters, among other possibilities.

Typically, a controlled amount of colorant is added to the mixture in extruder 106 and in each extruder 120 ₁, . . . , 120 _(N), for obtaining viscous plastic mixtures of respective specific colors. Different techniques, known in the art, may be used to color the plastic mixtures in the extruders 106 and 120 ₁, . . . , 120 _(N). In one example, colorant in the form of granules is added to and mixed with the plastic granules before they are fed into the extruders 106 and 120 ₁, . . . , 120 _(N) for melting. In another example, colorant in liquid form may be fed into the extruders for mixing with the plastic granules. Alternatively, the non-recycled plastic granules themselves can be pre-colored such that it is not necessary to add colorant to the mixture. In another alternative, recycled plastic granules of a specific color may be used in the extruders 106 120 ₁, . . . , 120 _(N), such that the addition of a colorant is not required.

In a specific practical implementation, the mixture “A” used in the primary extruder 106 may be a translucent material and the mixture “D” in the secondary extruders 120 ₁ may be a mixture of a specific color. Similarly, the mixture “E” in another secondary extruder 120 _(N) may be a mixture of a specific color, which may be the same or distinct from the color of mixture “D” used in the secondary extruder 120 ₁.

The primary extruder 106 is configured to melt and mix the plastic granules such that the mixture 110, which is released from extruder 106, is perfectly melted and homogeneous, both in temperature and in color, upon its exit from the extruder 106.

Similarly, a secondary extruder 120 is configured to melt and mix the plastic granules such that the mixture 122, which is released from a secondary extruder 120, is also perfectly melted and homogeneous, both in temperature and in color, upon exit from the extruder 120.

Note that, with regard to the plastic mixture released by the primary extruder 106, the term “melted” implies that the mixture is characterized by a viscous or semi-fluid flow. The plastic mixture 110 released is also referred to herein as a flow of a first viscous material 110. The extruder 106 releases the flow of the first viscous material at a first rate of flow. The first rate of flow may be any suitable rate flow depending on the type of extrudable material that is being created by the system 100, for example 400 kg/hr, 300 kg/hr, 100 kg/hr or 50 kg/hr, among many other possibilities. As will be described in greater detail later on in the present document, the flow of the first viscous material 110 may be provided at a first rate of flow that can be caused to vary over time.

With regard to the plastic mixture output by the secondary extruders 120 ₁, . . . , 120 _(N), the term “melted” also implies that the mixture is characterized by a viscous or semi-fluid flow. The plastic mixture 122 output by each extruder 120 is also referred to herein as a flow of a (second) viscous material 122. Each one of the secondary extruders 120 may be set to a respective rate of flow, for example 400 kg/hr, 300 kg/hr, 100 kg/hr, 50 kg/hr, 25 kg/hr or 10 kg/hr among many other possibilities. In the embodiment shown in FIG. 1, during the creation of an extruded material, the secondary extruders 120 ₁, . . . , 120 _(N) may be set to operate such as to release the plastic mixtures 122 at respective rates of flow that are kept substantially constant over time. It is however to be appreciated that, in alternate embodiments, the rates of flow of material released by any of the secondary extruders 120 ₁, . . . , 120 _(N) may be caused to vary over a time period so that flows of both the viscous material released by the primary extruder 106 and one or more of the secondary extruders 120 ₁, . . . , 120 _(N) are caused to vary over time. It is also to be appreciated that, in such alternative embodiments, the time intervals over which the viscous material released by the primary extruder 106 and the viscous material released by or more of the secondary extruders 120 ₁, . . . , 120 _(N) are caused to vary need not be the same.

The structure and functionality of extruders are well known to those skilled in the art, and will not be described in further detail.

In the embodiment depicted in FIG. 1, the primary extruder 106 is in communication with a flow rate controller 152 configured for varying over time the rate of flow of the viscous material 110 released by the primary extruder 106.

As depicted in FIG. 2, the flow rate controller 152 associated with the primary extruder 106 may include an electronic control element 606 configured for causing the first rate of flow of the viscous material 110 to vary over time. More specifically, and as shown in the specific embodiment depicted, the flow rate controller 152 may include a variable speed motor 604 configured for operating at different speeds an extruder screw 602 in the extruder 106. In this embodiment, the electronic control element 606 includes a processor (not shown) programmed for releasing control signals for controlling the speed of operation of the variable speed motor 604, which in turn causes a variation in a speed of rotation of the extruder screw 602 in the primary extruder 106. Any suitable manner for controlling the speed of operation of the variable speed motor 604 may be used and such manners are known in the art and will not be described further here.

In a specific practical implementation, the flow rate controller 152 may be configured for varying the first rate of flow over time at least in part by causing the first rate of flow to oscillate between a lower flow rate threshold and an upper flow rate threshold over a certain time interval.

In specific practical implementation, the lower flow rate threshold, the upper flow rate threshold and/or the time period may be preset, for example by a programmed element stored in the flow rate controller 152. Optionally, the lower flow rate threshold and/or the upper flow rate threshold and/or the time period may be set (or modified) by an operator of the system 100 in order to control at least in part visual characteristics of the color pattern in the stream of combined viscous material that will be generated by the system 100. For example by shortening the time period, more compact visual wave-like effects may be caused in the resulting output stream of combined viscous material while extending the time period may allow smoother/software visual wave-like effects to be created. The time period may be set to any suitable duration in dependence on the desired visual effect to be created in the extrudable material. In non-limiting practical implementations, the time interval used tends to range between about 20 seconds and about 1 minute. If we look now to the flow rate thresholds, increasing the upper flow rate threshold would tend to cause an increased volume of the first viscous material (“A”) to be pushed towards the feed block 104, which in turn causes a greater amount of this substance to find itself in the resulting output stream of combined viscous material. Analogously, decreasing the lower flow rate threshold would tend to cause a reduced volume of the first viscous material (“A”) to be pushed towards the feed block 104, which in turn causes a lesser amount of this substance to find itself in the resulting output stream of combined viscous material. Other variations can be made in the same manner to achieve different color patterns.

In the embodiment depicted in FIG. 2, the control of the first flow rate may be achieved by operating the variable speed motor 604 such as to cause the extruder screw 602 to vary its speed of rotation between an upper threshold and a lower threshold over a time period. FIGS. 4A and 4B show charts illustrating variations of the speed of operation of the extruder screw 602 over time in connection with extruder 106. It is to be appreciated that the examples shown in FIGS. 4A and 4B have been set forth for the purpose of illustration only and that many other suitable manners of varying over time the rate of flow of the viscous material 110 released by the primary extruder 106 may be contemplated and will become apparent to the person skilled in the art in view of the present description.

Optionally in some embodiments, such as the specific one depicted in FIG. 3, the electronic control element 606 of the flow rate controller 152 may provide one or more user operable controls 700 702 732 for allowing a user to set the lower flow rate threshold and/or the upper flow rate threshold and/or the time interval in order to control at least in part visual characteristics of the color pattern in the stream of combined viscous material exiting the system. The user operable controls 700 702 732 may include mechanically actuated switches that allow a user to providing control commands to increase or decrease a corresponding flow control parameter (for e.g. the lower flow rate threshold, the upper flow rate threshold or the time period). Optionally, display areas 704 708 734 may be provided showing values of the flow control parameters. It is to be appreciate that, although the electronic control element 606 shown in FIG. 3 has been shown as including a dedicated control interface incorporating user operable controls, in alternative embodiment such control interface may be provided on the display screen of a general purpose computing device in communication with the electronic control element 606 and programmed to display a control interface including user operable controls of the type described above.

In the context of the present invention, the extruder 106 and one or more of extruders 120 ₁, . . . , 120 _(N) produce plastic mixtures 110 122 of different colors and, optionally different viscosities. In a specific, non-limiting example, the system 100 may include a extruder 106 and one secondary extruder 120 ₁ which producing plastic mixtures 110 122. In another example, the system 100 may include one primary extruder 106 and two secondary extruders 120 ₁ 120 ₂ each of which is producing a plastic mixture of a different color and, optionally different viscosity.

In a practical embodiment, the plastic mixture 110 released by the (primary) extruder 106 is characterized by a first viscosity and the plastic mixture 122 released by the (secondary) extruder 120 has a second viscosity. The first viscosity and the second viscosity may be essentially the same or may be distinct from one another. The first viscosity may be lower (or higher) than the second viscosity. In embodiments in which there may be multiple (secondary) extruders 120, the plastic mixtures released by each (secondary) extruder may have the same (or similar) viscosity or, alternatively, may each have a distinct viscosity.

The use of materials having different viscosities may reduce an amount of color blending between the first color and the second color when the materials are combined in the feedblock 104 and static mixer 108 as will be described later on in the present document. The respective viscosities of the materials released by the (primary) extruder 106 and the (secondary) extruder(s) 120 may also be expressed in terms of high load melt index (HLMI). In this regard, the first viscous material may be associated with a first high load melt index (first HLMI) and the second viscous material may be associated with a second high load melt index (second HLMI). The first HLMI may be greater (or less) than the second HLMI.

It has been observed that using materials with differing HLMIs reduces the amount of blending between the materials. The greater the difference in high load melt index, the lesser the amount of blending appears to occur. The first HLMI may be at least about ten times (10×); at least about twenty times (20×); or at least about one hundred times (100×) the second HLMI. It is to be appreciated that, in practical implementations, the use of material having different viscosities may achieve different color effects compared to the use of materials of uniform viscosities and that such materials may be use alone or in combination with the variation in flow rate of the flow released by the primary extruder 106.

The plastic mixture 110 released by the (primary) extruder 106 and the one or more plastic mixtures 122 released by the one or more (secondary) extruders 120 ₁, . . . , 120 _(N) are then provided to the feed block 104.

The feed block 104 is configured for combining the flows 110 122 of viscous plastic output by the different extruders 106 120 ₁, . . . , 120 _(N) into a single patterned stream of combined viscous plastic, as will be discussed further below.

In the example depicted, the feed block 104 is comprised of multiple sequence feed blocks 104 ₁ . . . 104 _(N) where each feed block injects an additional stream of viscous material released by a respective secondary extruder 120 ₁, . . . , 120 _(N) into the stream of viscous material released by first (primary) extruder 106 or released by a previous feed block in the sequence. It will however be appreciated that other configurations for feed block 104 are possible in alternative implementations. For example, feed block 104 may be comprised of a single modules having N+1 input streams, where N corresponds for the number of secondary extruders 120 ₁, . . . , 120 _(N) in the system.

FIG. 6 illustrates a non-limiting example of a possible configuration for the feed block 104, for the case in which the system 100 is formed of one primary extruder 106 and two secondary extruders 120 ₁ and 120 _(N), wherein the primary extruder 106 releases a flow 110 of viscous material of a greater size than the flows 122 released by each of the secondary extruders 120 ₁ and 120 _(N). Thus, the feed block 104 receives three distinct flows 110 122 of viscous plastic, each of which is input to the feed block 104 from the associated extruder 106 and 120 ₁ and 120 _(N) via a respective feed port 270 200.

The feed block 104 also includes a programming section 202, which receives the flows 110 and 122 from the feed ports 270 200 into corresponding channels 284 204. This programming section 202 is operative to shape and position the flows 110 and 122 according to a predetermined pattern, whereby the flows undergo a programming of sorts within the channels 284 204 in order to produce a desired pattern for the stream of combined viscous material. In the example shown in FIG. 6, the channels 284 204 of the programming section 202 are designed to produce a pattern of layers where the layer associated with the flow 110 is shown as having a greater volume/size that the layers associated with the flows 122 to accommodate the higher flow rate of the first viscous material in the present example. It is to be appreciated that different sizes, shapes and layouts for the channels 284 204 of the programming section 202 may also be used, in order to produce different patterns for the stream of combined viscous material.

Note that the programming section 202 of the feed block 104 may be designed to divide a particular flow 110 or 122 into two or more sub-flows, for producing a different pattern for the stream of combined viscous material. In a specific example, assume the feed block 104 receives two flows 110 and 122, one that flow 110 is translucent in color and that flow 122 is red in color. The programming section 202 may divide the red flow 122 into two red sub-flows, and orient these sub-flows such that the translucent flow 110 is sandwiched between the two red sub-flows, according to a particular layout and pattern.

Finally, the feed block 104 includes a transition section 206, operative to fuse together the separate flows 110 and 122, for generating the patterned stream of combined viscous material. As seen in FIG. 6, the channels 288 208 of the transition section 206 are oriented such that their output ports 210 are located immediately adjacent one another. As the distinct flows 110 and 122 exit the respective output ports 210, the flows of the viscous plastics, fuse together into a single, combined stream of viscous plastic.

In the context of the present invention, the stream of combined viscous material generated by the feed block 104 is characterized by zones of material having different colors and, optionally, different viscosities. More specifically, at least one zone of material may be formed of a first viscous plastic material of a first color and first viscosity (material “A”) and another zone may be formed of a second viscous plastic of a second color and second viscosity (material “D”).

As mentioned above, the stream of combined viscous material released by the feed block 104 may take on different patterns, without departing from the scope of the present invention. Rather than a horizontal layer pattern, the feed block 104 may combine, the different flows 110 122 according to a vertical layer pattern, a ring pattern, a tube pattern or a pie chart pattern, among many other possibilities. In the case of the ring pattern, each separate flow 110 122 of viscous plastic may be formed into a concentric ring, where the rings of different colors and sizes are fused together to form a tube of combined viscous plastic characterized by adjacent zones of different colors and, optionally, different viscosities. In the case of the tube pattern, the separate flows 110 122 may be positioned with respect to one another such that, when fused together, they form an elongate tube, characterized by adjacent zones of different colors and, optionally, different viscosities.

FIGS. 9A, 9B, 9C and 9D show examples of cross-sections of combined streams of viscous material that may be generated using different practical embodiments of the feed block 104. For example, FIG. 9A shows examples of cross-sections including (a) a first viscous material (“A”) only; (b) first viscous material (“A”) and second viscous material (“D”); and (c) first viscous material (“A”), second viscous material (“D”) and third viscous material (“E”). It is to be understood that there is a myriad of other possible configurations and that the examples here have been shown for the purpose of illustration only.

Note that a generally uniform transition of the flows 110 122 from the extruders 106 120 to the feed ports 270 200 of the feed block 104, as well as from one component to another within the feed block 104, without any brusque variations in the channel dimensions may assist in reducing the likelihood of stagnation of the viscous plastic material within the feed block 104.

The use of feed blocks in extrusion processes is well known in the art and, as such, additional details pertaining to the feed block structure and functionality will not be described in further detail herein.

Specific to the present invention, the stream of combined viscous material released by the feed block 104 is fed through a static mixer pipe 108. The static mixer 108 is operative to act on the stream of combined viscous material for partially mixing the adjacent zones of different colors (and optionally different viscosities) in order to create color effects in the stream of combined viscous material.

Static mixers are known in the industry to be useful for effectively mixing fluids, by executing the operations of division of flow, radial mixing and flow reversal. The most common type of static mixer is the helical static mixer, as seen in the example of FIG. 7, which includes a series of static elements positioned adjacent another. Each element may be formed of a rectangular plate twisted by 180 degrees, which splits the oncoming flow in half and then turns it through 180 degrees. Each element in the series may be rotated 90 degrees with respect to the preceding element, so as to constantly subdivide the flow. When two fluids of different colors enter a static helical mixer pipe, the dividing and overturning motion applied to the fluids by the elements of the mixer results in a gradual blending of the two fluids. More specifically, as the fluids go along the curves of each element, they are rotated radially towards the pipe wall, or rotated back to the center. Furthermore, as the fluids pass from one element to the next, the fluids are bisected and they change direction to the right or to the left, the force of inertia that suddenly occurs creating a strong flow reversal motion that results in stirring and mixing of the fluids.

The color pattern in the stream released by the static mixer 108 is configured at least in part based on a radial orientation of the static mixer. The color pattern in the stream may be altered by performing a rotation of the static mixer 108 by a pre-determined rotation amount. The pre-determined rotation amount may be established based on an internal structure of the static mixer 108 such that upon exiting the static mixer a desired effect may be achieved in the stream of viscous material. In specific practical implementations, the pre-determined rotation amount may be a rotation of about 45°, 90°, 135° or 180° however other rotation amount may also be suitable for other static mixers.

Note that, for fluids of different types and/or viscosity, a different number of elements may be required in the static mixer in order to obtain a complete mixing of the two or more fluids from entry into the static mixer to output from the static mixer.

Different types of static mixers exist for uniformly mixing fluids in order to produce a homogenous mixture, such as the example shown in FIG. 8. Such static mixers are all designed around the same principle, notably passing the viscous fluids through a series of elements that cause the fluids to undergo different flow patterns resulting in the mixing of the fluids. The present invention is not limited to any particular type or design of static mixer.

Under the present invention, the static mixer 108 may be characterized by a specific number of elements, such that, upon exit from the static mixer 108, only a partial mixing of the different colored zones of the stream of combined viscous material has occurred, creating a blended, gradation in the colors of the stream of combined viscous material.

More specifically, upon entering the static mixer pipe 108, the stream of combined viscous material includes adjacent zones of first and second colors (and optionally first and second viscosities) respectively. The static mixer 108 is operative to mix together a portion of the zones such that, when the stream of combined viscous material exits the static mixer 108, the stream of combined viscous material may be characterized by zones of a third color, different from the first and second colors. It should be understood that the zones of color that exit the static mixer 108 are not necessarily clearly defined zones. In a first embodiment there can be a sharp transition between the color of one zone and the color of an adjacent zone, thereby creating clearly defined zones. However in an alternate embodiment, there can be a slow color gradation from the color of one zone to the color of an adjacent zone, such that the border between the two zones is not clearly defined. In addition, the shapes of the zones can vary. For example, the zones can be substantially straight, or can be wavy or curved. Likewise, the zones can be horizontally oriented, vertically oriented, or diagonally oriented at any angle between horizontally oriented and vertically oriented.

Typically, when the stream of combined viscous material exits the static mixer 108, the third zone of a third color is a combination of the colors of the first and second zones. For example, if the stream of combined viscous material that enters the static mixer 108 includes a first zone that is yellow and a second zone that is red, then typically, the stream of combined viscous material that exits the static mixer may include a third zone that is a shade of orange.

Alternatively, when the stream of combined viscous material exits the static mixer 108, the third zone of the third color is not necessarily located between the first and second zones of the first and second color. Instead, it is possible that the third zone of the third color is located between two zones of the first color, or two zones of the second color. For example, if the stream of combined viscous material that enters the static mixer 108 includes a first zone that is white and a second zone that is blue, then the stream of combined viscous material that exits the static mixer may have a third zone that is a lighter shade of blue. As such, it should be understood that for the purposes of the present invention, the third color can be a lighter shade of one of the first and second colors. In addition, it is possible that the stream of combined viscous material that exits the static mixer 108 will not include a zone of white, and that instead the stream of combined viscous material includes a zone of the light blue located between two zones of the blue that entered the static mixer.

Note that the static mixer pipe 108 may include two or more static mixers, for acting simultaneously on different portions of the stream of combined viscous material as the stream passes through the pipe 108.

Take for example the case where the system 100 includes a first extruder 106 producing a flow 110 of translucent viscous plastic, a second extruder 120 ₁ producing a flow 122 of blue viscous plastic and a third extruder 120 ₂ producing a flow 122 of yellow viscous plastic. Assume that the feed block 104 is operative to combine these three separate flows 110 122, characterized by: (a) a zone of yellow; (b) a zone of blue and (c) a translucent zone. With reference to FIG. 9A(c) and FIG. 10, as this combined stream passes through the static mixer pipe 108, the three zones of color are partially mixed together. Thus, other zones, green in color, may be created around the yellow and blue zones of the stream as well as around the translucent zones. Additional zones of color may also be created, located between the green zone and the yellow zone, as well as between the green zone and the blue zone. Upon its exit from the static mixer 108, the stream of combined viscous material of viscous plastic may include a gradation in color from yellow to blue, and includes zone of different colors.

Note that the length of the static mixer 108 that is necessary to obtain a partial mixing of the different colored zones of the stream of combined viscous material of viscous plastic may vary for different implementations of the system 100. The present invention is not limited to any specific length, or number of elements, for the static mixer pipe 108.

The selection of an appropriate static mixer 108 is based on certain predetermined parameters, including the diameter, length and orientation of the elements themselves within the static mixer 108. Furthermore, the determination of the appropriate dimensions for the static mixer 108 will depend on the type of plastic material in use within the system 100, as well as the respective rate of flow for each extruder 106 120 ₁, . . . , 120 _(N) and the total rate of flow for the stream of combined viscous material output by the feed block 104

In a specific, non-limiting example, in order to create a sheet of plastic having a red-orange-yellow wave-like appearance once it has exited the static mixer 108, a first extruder having a 3^(1/2) inch diameter is supplied with new plastic granules and 4% red colorant, and a second extruder having a 1^(1/2) inch diameter at 75 rpm is supplied with new plastic granules and 4% yellow colorant. In this non-limiting example, the first extruder is operated at a variable speed that fluctuates between about 15 rpm and 50 rpm over a 40 second time interval. From the extruders, viscous flows of red and yellow plastic are fed into a feedblock that forms the flows of red and yellow plastic into a stream of adjacent zones, which it feeds into a helical static mixer having a 2½ inch diameter made of 3 elements.

In another specific, non-limiting example, in order to create a sheet of plastic having a blue, white and light blue appearance once it has exited the static mixer, a first extruder having a 3^(1/2) inch diameter is supplied with new plastic granules and 2% white colorant, and a second extruder having a 1^(1/2) inch diameter at 70 rpm is supplied with new plastic granules and 4% blue colorant. In this other non-limiting example, the first extruder is operated at a variable speed that fluctuates between about 12 rpm and 60 rpm over a 20 second time interval. From the extruders, the flows of white and blue viscous plastic are fed into a feedblock that forms the two flows into a three layer stream of blue, white and blue which it feeds into a helical static mixer having a 2^(1/2) inch diameter made of 6 elements.

Note that different orientations of the static mixer 108 with respect to the longitudinal plane of the stream of combined viscous material will result in different patterns of color gradation in the stream of combined viscous material at the output of the static mixer pipe 108. For example, in the case of a helical static mixer 108, if the last element of the static mixer 108 is oriented horizontally with respect to the plane of the stream of combined viscous material, the static mixer 108 will tend to produce longitudinal bands of color in the stream of combined viscous material. In contrast, if the last element is oriented vertically with respect to the plane of the stream of combined viscous material, the static mixer 108 will tend to produce vertical bands of color in the stream of combined viscous material.

Furthermore, different orientations of the static mixer 108, as well as different rates of flow for the different extruders 106 120 ₁, . . . , 120 _(N), may produce colored zones of different sizes within the stream of combined viscous material. Thus, the final color pattern achieved in the stream of combined viscous material by the static mixer 108, including both size and color dominance, is dependent on the respective rate of flow of the extruders 106 120 ₁, . . . , 120 _(N), as well as on the orientation of the static mixer 108.

The die 102 receives the stream of combined viscous material from the static mixer pipe 108, and is operative to shape the stream of combined viscous material into its final product form, such as a sheet or a tube, among many other possibilities. In the non-limiting example shown in FIG. 1, the die 102 is operative to produce sheets of plastic 112 from the stream of combined viscous material. Different shapes and sizes of dies may be used within the system 100 to generate different forms and types of plastic products. The structure and functionality of such dies are well known to those skilled in the art, and as such will not be described in further detail herein.

FIGS. 11A and 11B illustrate two examples of products that may be formed by the die 102. In FIG. 11A is shown an example of a sheet of plastic resulting from a three-color (translucent, yellow and blue) extrusion process. In its final product form, the sheet of plastic is characterized by wave-like color gradation effects including translucent zones (the color “A” from the first extruder 106), as well as waves of blue (the color “D” from extruder 120 ₁), of yellow (the color “E” from extruder 120 _(N)) and waves of green (resulting from a partial blending of color “D” and color “E”).

In FIG. 11B is shown an example of a tube of plastic resulting from the same three-color extrusion process.

The product resulting from the extrusion process described in the present document, such as the sheet or tube of plastic, may be used as is, in different applications. For example, the sheets of plastic may be cut out to form tobogganing carpets, also referred to as crazy carpets. Alternatively, the product resulting from the extrusion process may be thermoformed into different shapes or final products. For example, the sheets of plastic characterized by the wave-like color gradation effects may be thermoformed into pedal boats, kayaks, canoes, stand-up paddle boards or other similar watercraft products. They may also be thermoformed into recreational products, such as toboggans and pools, among many other possibilities. Whether thermoformed or not, a main advantage of the extruded product resulting from the above-described extrusion process is to provide an esthetically appealing appearance to the consumer or user.

FIG. 14A shows kayaks manufactured using one or more plastic sheets of extrudable material with wave-like color gradation effects created using a process embodying aspects of the invention described in the present document.

More specifically, kayaks of the type depicted in FIG. 14A may be manufactured by molding two or more of the manufactured sheets of extrudable material using thermoforming to shape the two of more manufactured sheets into a kayak shape. In such process, one or more of the two or more of the manufactured sheets may have color effects created using a process embodying aspects of the invention described in the present document.

FIGS. 14B and 14C show top plan and side views respectively of a stand-up paddle board (SUP) manufactured using plastic sheets of extrudable material created using a process embodying aspects of the invention described in the present document.

FIG. 12 is a flowchart illustrating a process that may be implemented by the system 100 for creating color gradation effects in extruded plastic material.

As shown, at step 1200, a flow of a first viscous material of a first color is provided through the primary extruder 106 (shown in FIG. 1). The first viscous material (material “A”) is released by the primary extruder 106 at a first rate of flow. In a first specific implementation, when providing the first viscous material (material “A”), the first rate of flow may be caused to vary over time. Varying the rate of flow of the first viscous material over time may allow modulating over time an amount of the first viscous material (material “A”), relative to an amount of the second viscous material (material “D”) that finds itself in the stream of combined viscous material at different moments in time, which may allow the color effects created to vary over time and create wave-like patterns.

FIG. 5A shows color effects that may be produced in extrudable plastic material using the system 100 in which the flow rate controller 152 maintains a generated constant first flow rate in connection with extruder 106 (in other words no flow rate variation is applied to extruder 106). FIG. 5B shows color effects that may be produced in extrudable plastic material using the system 100 in which the flow rate controller 152 varies the flow rate of the extrudable material 1101. As can be observed, the modulation of the flow rate may allow creating wave-like color gradation effects in the resulting plastic material.

In one of the non-limiting practical embodiments contemplated, the first viscous material “A” is a base or carrier color. For example, the first viscous material “A” may be a translucent material and/or a neutral color such as a white (or off white), grey or any other suitable base of color.

At step 1202, which is performed concurrently with step 1200, a flow of a second viscous material of a second color, different from the first color, is provided through one of secondary extruders 120 (shown in FIG. 1) The second viscous material (material “D”) is released by the secondary extruder 120 at a second rate of flow. In a first specific implementation, when providing the second viscous material (material “D”), the second rate of flow is kept substantially constant over time. It is however to be understand that this need not be the case in all implementations and that the second flow rate may also be caused to vary over time in a manner similar to that described above with reference to the flow of the first viscous material.

In some specific practical implementations, the second rate of flow associated with the second viscous material of the second color may be lower than the first rate of flow. In such implementations, the first viscous material (“A”) constitutes a larger portion of the resulting stream of combined viscous material than the second viscous material (“D”). In specific practical implementations, the second rate of flow may be no more than 50% of the first rate of flow, preferably no more than 30% of the first rate of flow and more preferably no more than 20% of the first rate of flow.

In one of the non-limiting practical embodiments contemplated, the second viscous material “D” is an accent color intended to be carried by the base (or carrier color) of material “A”. For example, the second viscous material “D” may be a bright colored material and such as a red, blue, pink, green, yellow or any other color that may add visual interest to the base (or carrier color) of material “A”.

In some implementations, the second viscous material “D” provided at step 1202 may have a viscosity that is distinct from the viscosity of the first viscous material “A” to reduce an amount of color blending between the first color and the second color in the stream of combined viscous material.

At step 1204, the first and second flows are combined together in the feed block 104 (shown in FIG. 1) in a predetermined pattern to form a stream of combined viscous plastic.

Next, at step 1206, the stream of combined viscous plastic generated at step 1204 is fed through the static mixer 108 (shown in FIG. 1), which is configured to partially mix the first viscous material (“A”) and the second viscous material (“D”) such that upon exiting the static mixer, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material. In some cases, the color pattern created includes zones of the first color, zones of the second color and (optionally) zones of a third color, different from the first and second colors. The third color is typically a blend between the first color and the second color.

In cases where, the second viscous material “D” provided at step 1202 has a viscosity that is distinct from the viscosity of the first viscous material “A”, colors may tend to remain more true to the original first and second colors, and exhibit less color blending, than in cases where the viscosities of the first and second viscous materials are substantially the same.

Note that the above process may be applicable to various different suitable types of extrudable material, and is not limited to plastic applications.

FIG. 13 depicts a system 800 for manufacturing plastic sheets, according to an alternative example of implementation of the present invention. As shown, system 800 is used for manufacturing plastic products, such as plastic sheets, with color effects being provided in one or more surface layers of the product. In this case, extruder 806 ₁, which includes extruder 816 connected to flowrate controller 852 as well as extruders 860 ₁, . . . , 860 _(N), in combination with the feed block 804 (which in this example is comprises of feed block sequence 804 ₁ . . . 804 _(N)) and the static mixer 808, produces a stream of combined viscous plastic 810 ₁ characterized by color effects, in a similar manner as described above with regard to the system 100 (shown in FIG. 1).

This stream 810 ₁ is then fed into a combining device where it is combined with the separate flows 800 of viscous plastic output by the extruders 806 ₂, . . . , 806 _(N). In the specific example shown in FIG. 13, the combining device includes the feed block 812. The feed block 812 produces a co-extruded stream of viscous plastic 810 ₂, having at least one layer, typically a surface layer, characterized by color effects. The die 814 then receives this co-extruded stream 810 ₂, and is operative to mold the plastic stream into its final form, for example a sheet or a tube.

Note that the feed blocks 804 and 812 may be similar in structure and functionality to that described above with regard to the feed block 104.

In an alternative embodiment wherein the die 814 is configured to combine the streams from the static mixer pipe 808 and the extruders 806 ₂ 806 _(N) into a co-extruded sheet prior to forming the sheet into its final form, the feedblock 812 can be omitted, and the combining device may simply include the die 814.

Thus, in this variant example of implementation, plastic products are formed in which the color effects may be limited to an outer surface of the product. Note that, in this case, one or more of the extruders 806 ₂, . . . 806 _(N) may be fed with recycled plastic granules, if the respective one or more layers of plastic generated by these extruders are not visible on the finished product. Alternatively, each of the extruders 806 ₂, . . . 806 _(N) may be producing a plastic mixture of a predetermined and specific color, depending on the specific applications and end products being formed.

Note that any one of the extruders 806 ₂, . . . 806 _(N) may be set up in the same way as extruder 806 ₁, such that two or more layers of the final plastic product are characterized by color effects. These color effects may differ from one layer to another, since the extruder flow rates and static mixer orientations may vary from one extruder arrangement to the other.

Alternatively, the die 814 may be provided with multiple feed ports, such that the die 814 itself could directly receive the stream of viscous plastic 810 ₁ from the extruder 806 ₁, as well as the flows 800 from the extruders 806 ₂, . . . 806 _(N). Thus, the die 814 would act to combine the stream 810, and the flows 800 into the co-extruded stream of viscous plastic 810 ₂, after which the die 814 would shape the stream 810 ₂ into the final product form. Note that, in this case, the die 814 takes on the responsibility of the feed block 812, which is no longer required within the system 800.

Although various embodiments have been illustrated, this was for the purpose of describing, but not limiting, the invention. Various modifications will become apparent to those skilled in the art and are within the scope of this invention, which is defined more particularly by the attached claims.

The foregoing is considered as illustrative only of the principles of the invention. Since numerous modifications and changes will become readily apparent to those skilled in the art in light of the present description, it is not desired to limit the invention to the exact examples and embodiments shown and described, and accordingly, suitable modifications and equivalents may be resorted to. It will be understood by those of skill in the art that throughout the present specification, the term “a” used before a term encompasses embodiments containing one or more to what the term refers. It will also be understood by those of skill in the art that throughout the present specification, the term “comprising”, which is synonymous with “including,” “containing,” or “characterized by,” is inclusive or open-ended and does not exclude additional, un-recited elements or method steps.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the case of conflict, the present document, including definitions will control.

Although the present invention has been described in considerable detail with reference to certain embodiments thereof, variations and refinements are possible and will become apparent to the person skilled in the art in view of the present description. The invention is defined more particularly by the attached claims. 

The invention claimed is:
 1. A process for manufacturing a sheet of material with color gradation effects resembling waves on at least one surface, said process comprising: a) providing a flow of a first viscous material of a first color, wherein the first viscous material flows at a first rate of flow and wherein providing the flow of the first viscous material of the first color includes varying the first rate of flow over time; b) providing a flow of a second viscous material of a second color different from the first color, wherein the second viscous material flows at a second rate of flow, wherein the second rate of flow is lower than the first rate of flow and wherein the second rate of flow is kept substantially constant over time; c) combining the flow of the first viscous material and the flow of the second viscous material to form a stream of combined viscous material, the stream of combined viscous material formed by said combining being characterized by bands of colored extruded material longitudinally extending along the stream; d) applying a dividing, overturning and combining motion to said stream of combined viscous material to partially mix the first viscous material and the second viscous material, such that following the applying of the dividing, overturning and combining motion, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material; e) feeding the stream of combined viscous material through a die for forming the sheet of material, wherein the color pattern in the stream of combined viscous material creates the color gradation effects resembling waves on the at least one surface of the sheet material as the stream of combined viscous material is fed through the die, the color gradation effects being created in extruded material, said sheet of material being configured for being shaped into a consumer article using thermoforming.
 2. The process defined in claim 1, wherein varying the first rate of flow over time includes causing the first rate of flow to oscillate between a lower flow rate threshold and an upper flow rate threshold over a time interval.
 3. The process defined in claim 2, wherein said process comprises setting at least one of the lower flow rate threshold, the time interval and the upper flow rate threshold in order to control at least in part visual characteristics of the color pattern in the stream of combined viscous material.
 4. The process defined in claim 3, wherein setting at least one of the lower flow rate threshold, the time interval and the upper flow rate threshold includes entering control commands on a computer operated control circuit.
 5. The process defined in claim 1, wherein said first viscous material has a first viscosity and said second viscous material has a second viscosity, said first viscosity being different from said second viscosity.
 6. The process defined in claim 5, wherein said first viscous material is characterized by a first high load melt index and wherein said second viscous material is characterized by a second high load melt index, said first high load melt index being less than said second high load melt index.
 7. The process defined in claim 1, wherein said first viscous material and said second viscous material are viscous plastic materials.
 8. The process defined in claim 7, wherein the first color of the first viscous material is a translucent color.
 9. The process defined in claim 1, said process comprising using a static mixer to apply the dividing, overturning and combining motion to said stream of combined viscous material to partially mix the first viscous material and the second viscous material.
 10. A process for manufacturing a plastic article, said process comprising: a) manufacturing sheets of material having color gradation effects resembling waves on at least one surface, wherein manufacturing said sheets comprises: i) providing a flow of a first viscous plastic material of a first color, wherein the first viscous plastic material flows at a first rate of flow and wherein providing the flow of the first viscous plastic material of the first color includes varying the first rate of flow over time between a lower flow rate threshold and an upper flow rate threshold; ii) providing a flow of a second viscous plastic material of a second color different from the first color, wherein the second viscous plastic material flows at a second rate of flow, wherein the second rate of flow is lower than the lower flow rate threshold and wherein the second rate of flow is kept substantially constant over time; iii) combining the flow of the first viscous plastic material and the flow of the second viscous plastic material to form a stream of combined viscous plastic material, the stream of combined viscous material formed by said combining being characterized by bands of colored extruded material longitudinally extending along the stream; iv) applying a dividing, overturning and combining motion to said stream of combined viscous plastic material to partially mix the first viscous plastic material and the second viscous plastic material, such that following the applying of the dividing, overturning and combining motion, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous plastic material; v) forming the sheets of material having color effects created in extruded plastic material at least in part by feeding the stream of combined viscous plastic material through a die, wherein the color pattern in the stream of combined viscous material creates the color gradation effects resembling waves on the at least one surface of the sheet material as the stream of combined viscous material is fed through the die, the color gradation effects being created in extruded material; b) molding one or more of the manufactured sheets using thermoforming to shape the one or more manufactured sheets into the plastic article.
 11. A process for manufacturing a kayak, said process comprising molding two or more manufactured sheets of extruded material using thermoforming to shape the two or more manufactured sheets into a kayak shape, at least one of the two or more of the manufactured sheets having color gradation effects resembling waves on at least one surface created using a process comprising: a) providing a flow of a first viscous material of a first color, wherein the first viscous material flows at a first rate of flow and wherein providing the flow of the first viscous material of the first color includes varying the first rate of flow over time between a lower flow rate threshold and an upper flow rate threshold; b) providing a flow of a second viscous material of a second color different from the first color, wherein the second viscous material flows at a second rate of flow, wherein the second rate of flow is lower than the lower flow rate threshold and wherein the second rate of flow is kept substantially constant over time; c) combining the flow of the first viscous material and the flow of the second viscous material to form a stream of combined viscous material, the stream of combined viscous material formed by said combining being characterized by bands of colored extruded material longitudinally extending along the stream; d) applying a dividing, overturning and combining motion to said stream of combined viscous material to partially mix the first viscous material and the second viscous material, such that following the applying of the dividing, overturning and combining motion, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material; e) feeding the stream of combined viscous material through a die for forming the at least one of the two or more of the manufactured sheets, wherein the color pattern in the stream of combined viscous material creates the color gradation effects resembling waves on the at least one surface of the sheet material as the stream of combined viscous material is fed through the die, the color gradation effects being created in extruded material.
 12. A process for manufacturing a sheet of material with color gradation effects resembling waves, said process comprising: a) providing a flow of a first viscous material of a first color, wherein the first viscous material flows a first rate of flow and wherein providing the flow of the first viscous material of the first color includes varying the first rate of flow over time; b) providing a flow of a second viscous material of a second color different from the first color, wherein the second viscous material flows at a second rate of flow, wherein the second rate of flow is lower than the first rate of flow and wherein the second rate of flow is kept substantially constant over time; c) combining the flow of the first viscous material and the flow of the second viscous material to form a stream of combined viscous material, the stream of combined viscous material formed by said combining being characterized by bands of colored extruded material longitudinally extending along the stream; d) applying a dividing, overturning and combining motion to said stream of combined viscous material to partially mix the first viscous material and the second viscous material, such that following the applying of the dividing, overturning and combining motion, the first material of the first color and the second material of the second color form a color pattern in the stream of combined viscous material; e) providing at least one additional flow of a third viscous material; f) combining the stream of combined viscous material with the at least one additional stream of third viscous material to form a co-extruded stream; and g) feeding the co-extruded stream through a die for forming the sheet of material having a surface layer and at least one other layer, wherein the color pattern formed by the first material and the second material creates the color gradation effects resembling waves on the surface layer of the sheet material as the co-extruded stream is fed through the die, the color gradation effects being created in extruded material, said sheet of material being configured for being shaped into a consumer article using thermoforming. 